gas_heater_explanationHydronic Boilers require a water top up from time to time, this is just a natural occurrence of Hydronic Heating systems. It is quite a simple process that you can do yourself with the following instructions.

1. Turn the blue knob (highlighted by the blue square) vertical until it is parallel with the pipe it is attached to.

2. DO NOT touch the front black knobs (highlighted by the red box). This is preset to the correct water pressure.

3. Turn the REAR black knob anti-clockwise (highlighted by the green box). 

You may or may not hear a slight water-rushing sound as the unit fills with water, this should take approximately 20-30 seconds. You should notice the pressure gauge, as shown below, increase to the correct pressure. Reverse the taps but to their original position and the boiler should fire up immediately. Contact the Mercury office if you notice any error codes on the digital screen shown in the image below.


4. You want to check this pressure gauge (highlighted by the blue square) to ensure that you get the boiler back to the optimal level. It should read between 1 and 1.5.